Molding method and apparatus



Dec. 17, v1929. Q E, FOERSTNER 1,740,082

MOLDING METHOD AND APPARATUS Filed April 6, 1928 2 Sheets-Sheet l Dec. 17, 1929. y G E, FOERSTNER 1,740,082

MOLDING METHD AND APPARATUS Filed April 6; 1928 2 Sheets-Sheet 2 75m? E EFUEES/FYEE E fw) JAAR f j?? V45 Fi 1 is a side elevation of apparatus emin registry with thel respective apertures 18 Patented Dea-17,Y 1929V I UNITED `STATI-:fs PATENT oFrlcE-A" GEORGE E. FOERSTNEB, OF AKRON, OHIO, ASSIGNOR TO THE B. F. GOODRICH COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW YORK nonnina METHOD AND Arrnitafrus application nica April 6, 192s. serial No. ceases.

This invention relates to procedure and ap- Fig. 4 is a fragmentary vertical section on paratus for molding plastic material by the a larger scale of parts of the apparatus in the extrusion method and especially for molding vicinity of one of the extrusion apertures. small articles, such as rubber' shoe-lleels or Referring to the drawings, the apparatus small porcelain articles such as electric incomprises a base centrally formed with sulators, in large numbers. Heretofore -ara ram cylinder 11 is which is mounted an ticles such as shoe-heels have been molded of upwardly projecting ram 12 liaviiig'sccured rubber composition by moving a multi )leon its upperend a supportin'gfanl guiding cavity mold past the delivery aperture o an head 13 for a multiple-cavityimold 14.

10 extrusion device in stock-receiving relation A pair of standards 15, 15 rise from the i'e- C0 thereto,y the stock forced into each Cavity Spective sides ofthe base 10. .Ataposition inbeing sheared oli from the supply mass of termediate of their height they are connected Y stock at the mouth of the cavity as an incident by a steam jacket, extrusion chamber casting of the cavity passing out of communication 16 which is centrally formed with an up 15 with the delivery aperture. In such procewardly opening extrusion chamber 17 having dure each cavity has been lled progressively a floor 16a formed with numerous extrusion from one side thereof to the other, the moveapertures such as the apertures 18, 18 so ment of the mold being continuous for the lillspaced apart as to be `'lin registry with re- 2 ing ofa succession of the cavities therein, and spective cavities such a's the cavities 19, 19

0`the ow of the stock into the cavity conseof the mold 14 when the latter is properly 70 uently has -not been symmetrical with relapositioned Aupon the ram head 13 and held tion thereto, which may nnfavorably affect upward a ainst the extrusion chamber asthe grain characteristics of the stock, or the sembly. he extrusionl chamber Vcasting 16 mold has been intermittently moved and when adapted for extrusion of a heat-plastic stopped with one after another of afile of substance such l as an unvulcanized rubber 75 cavities in communication with the extrusion composition is preferably formed with a aperture, which has required a relatively steam passage 20 surrounding the extrusion long time for the filling of the'multiple-cavchamber for the circulation of steam through ity mold. the casting to keep in a highly plastic condi- My chief objects are to provide for symtion a supply mass of rubber composition 21 80 metrical flow of the stock into each mold cavcontained in the chamber. it?, toprovide economy of time in the filling On its lower side the extrusion chamber o a multiple-cavity mold, and, in apparatus casting 16 is formed at opposite sides with 3f including an extrusion device constructed undercut flanges 22, 22 defining guide Ways for complete enclosure and high compression for res ective side margins of a die, shear- 85 ofthe supply mass ofstock,to provide convening an closure plate 23 which is formed ient-ly for the accommodation of a large supwith downwardly tapered apertures such as ply mass of stock and thus to avoidV the nelthe apertures 24, 24 'each being at the upper o cessity of frequent opening and refilling of face of the plate the same size as the aperture the extrusion device. 18 in the extrusion chamber floor-16" and 90 A further object is to provide a tight seal atthe lower face of the late being of small between the mold and t e extrusion device size as compared with t e size of the mold and'thus to avoid wasteful escape of stock. cavity 19, so that when the plate 23 is moved 0f the accompanying drawings: into a position such that its apertures 24 are 95 bodying and adapted to carry out my invenandthe respective mold cavities 19, the extionin its preferred form.- trusion chamber 17 will have communication Fig. 2 is a section of the same'on line 2-7-2 with all of the mold cavities through ppen of Fig. 1. passages, 18, 24, terininating'in comparatively Fig. 3 is a section on ),ine 3-3 of Fig. 2.l 'smallmeuths centrally with relation to the respective mold cavities, so that a flow guide ways to register its apertures withthe apertures 18 and alternately to move the plate out of registry with the extrusion apertures and thus to shear off from the supply mass 21 the stock contained within the mold cavities 19 and at the same time close the apertures 18,.the plate 23 is secured at the end of the piston rod 25 of a horizontal double-acting iluid pressure cylinder 26 adapted forcibly to eiect the reciprocal movement of the plate although the plate may be tightly grip ed between the floor 16a of the extrusion c amber and the mold 14 under the force of the ram 12.

The means for forcing the plastic stock 21 from the chamber 17 through the die apertures comprises a plunger or ram head 27 f slidably fitting in the chamber 17 and secured upon the lower end of the piston rod 28 of a double-acting fluid pressure cylinder 29 formed in a casting 30 sccured to and connecting the upper ends of the standards 15.

.A conveyor 31 is provided for delivering successive molds such as the mold 1,4 onto the y ram head 13 and a stop device comprising a pair of stop arms 32,` 32 pivptedon the ram head 13fis provided for accurately positioning the successive molds upon the ram head.

The stop arms 32 are turnable about their pivots to positions such that they lie entirely below the upper face of the ram head 13, to permit the mold to be shoved from the ram lead onto a receiving conveyor 33, and for vturning the stop arms their lower ends are pivoted to a handle rod 34.

Guide rails 35, 35 are secured upon the upper face of the ram head 13 for accurately positioning the successive molds 14 with relation'to the'extrusion device and for guidf ingthe molds from the ram head onto the recelving conveyor 33.

In the operation of the apparatus, the eX- trusion chamber 17 being charged with the supply mass of plastic 21 and the shearingy and closure -plate 23 being positioned with its apertures 24 out of registry with the apertures 18 of the extrusion chamber floor and the ram 12 being lowered, one of theV molds 14 is shoved from the delivery conveyor 31 onto the ram head and is positioned thereon between the guide rails 35 and against the stop arms 32. The ram 12 is then raised to present the Amold to. and hold it pressed against the under face of the shear plate 23.

I H The shear plate is then moved by means of the fluid pressure cylinder 26 to bring its apertures in registr with -those of the eX- trusion chamber an the extrusion ram'27 is eration as described When the, mold cavities arey filled and' pref' erably While the stock therein is held under high pressure by the forcey of the extrusion ram 28, the plate 23 is mov-ed out o f registry with the apertures'18 of the extrusion cham-vv ber, by reversal ofthe fluid pressure cylinder 26, such movement of the plate 23 closlng off the extrusion passages 18 and shearing olf from the supply mass of stock and from the stock in the apertures ofthe plate 23, the stock held under compression in the mold cavities. It is not entirely essential, however, that high pressure be maintained upon either the extrusion ram 28 or the mold-lifting ram 12 during such movement of the plate 23 or during the reverse movement of the said plate, the stock initially having been thoroughly compressed in the mold cavities, and consequently the apparatus ma be so operated that the shearing action o the plate 23 is effected without requiring a very great force, although the mold is very forcibly held against the plate 23 during the mold-filling flow of stock so that leakage or overflow of the stock from the mold cavities is`avoided. When the mold has been illed and the stock in its several cavities has thus been sheared ofi' from thesupply mass and the outlets from the extrusion chamber 17 have been closed by the plate 23, the ram 12 is lowered and the mold is shoved therefrom onto the receiving conveyor 33, and the opis repeated' with successive molds. v

Modifications are possible within the scope of my invention as defined inthe appended claims.

I claim:

1. The method ofl molding plastic material which comprises concurrently forcing stock from a single supply7 mass'by extrusion into a plurality ofmold cavities and, while holding the stock undervpressure in the several cavities by pressure applied to the supply mass, shearing olf from the supply mass the masses of stock Within the respective cavities, the supply mass as a Whole being held in substantially the same position with relation to the mold throughout the filling of the mold cavities and throughout the shearing oi op.- eration. i

`2.' Moldingapparatus comprising an extrusion chamber formed with an extrusion aperture in a wall thereof, a shear plate mounted against the outer face of said wall and formed with an extrusion aperture, the plate being slidable with relation to said wall to efl'ect registry and non-registry of the two said extrusion apertures with each other, a cavitied mold, and means for holding the mold with its cavity in stock-recei-vn relation to the 'extrusion aperture of the p ate.

3. Molding apparatus comprising an extrusion chamber'formed with an extrusion aperture in a wall thereof, a shear plate mountedagainst the outer fa of said wall and forme with an extrusion aperture, the

plate being-slidablewith relation to said wall to effect registry and non-registry of the two said extrusion apertures with each other, a cavitied mold and means for holding the mold against t e plate with variable pressure and with the cavlty of the mold in stock-receiving relation` to the extrusion aperture of the plate.

In witness whereof I have hereunto set my l hand this 30th da of March, 1928.

' e GEO GE E. FOERSTNER. 

